Can someone please advise me on how to measure flush flow rates (i.e., urinals, water closets)? I know LEED wants us to do measurements for a 20% sample of fixtures with unknown flow rates. I'm working with an old 1954 building and existing fixtures do not have nameplates! Do I need to hire a plumber?

Also, is it possible to submit a customized excel sheet for my calculations instead of the LEED online worksheet?

Please help. Thanks.